The Type Four chassis was a common front wheel drive platform used in the 1980s and 1990s for the Saab 9000, Fiat Croma, Lancia Thema and Alfa Romeo 164.It emerged as an agreement between the four carmakers in October 1978 to reduce development costs on new top-of-the-range saloons, although it would be another six to nine years before the cars were launched.The Fiat and Lancia looked much like the Saab, but the Alfa Romeo only shared the chassis.